Alternative Fuels | SciByte 4

Alternative Fuels | SciByte 4

This week on SciByte …
We take a look at a few alternative fuel choices, what they come from, some interesting facts about them, and even some of the chemistry involved.

All that and more, on SciByte!

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Show Notes:


  • Are a wide range of biologically produced alcohols, most commonly ethanol, and less commonly propanol and butanol
  • Produced by the action of microorganisms and enzymes through the fermentation of sugars or starches (easiest), or cellulose (which is more difficult)

Bioethanol Chemistry [fermenting the sugar components of plant materials]

  • Photosynthesis
  • → 6 CO2 + 6 H2O + light → C6H12O6 + 6 O2
  • → [ Carbon dioxide + Water + Light → Glucose + Oxygen ]
  • Ethanol Fermentation
  • → C6H12O6 → 2 C2H5OH+ 2 CO2 + heat
  • → [ Glucose → Ethanol + Carbon dioxide + heat ]
  • Combustion
  • → C2H5OH + 3 O2 → 2 CO2 + 3 H2O + heat
  • → [ Ethanol + Oxygen → Carbon dioxide + Water + heat ]

Ethanol / ethyl alcohol – Overview

  • The same type of alcohol found in alcoholic beverages.
  • Brazil & United States were responsible for 88% of the world’s ethanol fuel production in 2010
  • Most cars on the road today in the U.S. can run on blends of up to 10% ethanol.
  • Since 1976 the Brazilian government has made it mandatory to blend ethanol with gasoline, and since 2007 the legal blend is around 25% ethanol and 75% gasoline
  • Ethanol has a smaller energy density than gasoline, which means it takes more fuel (volume and mass) to produce the same amount of work.
  • An advantage of ethanol (CH3CH2OH) is that it has a higher octane rating than ethanol-free gasoline available at roadside gas stations which allows an increase of an engine’s compression ratio [ratio of the volume of its combustion chamber from its largest capacity to its smallest capacity] for increased thermal efficiency
    • High octane prevents pre-ignition from pressure/heat, and allows the spark plugs to ignite the fuel at the proper time.
    • A high compression ratio allows more power per piston stroke. (more efficient)

Corn Facts

  • Corn ethanol has now replaced 8 percent of American gasoline.
    • Byproducts of corn ethanol can be used as animal feed, and not discarded.
  • In 2010, the state of Iowa, produced more corn than the entire United States did in 1947.
  • Of our entire corn crop, only 2 percent is actually eaten by Americans as corn, or 12 percent if one includes products like corn chips and corn syrup.
  • There are downsides to considering the widespread use of Corn Ethanol as a primary fuel source:
    • Most notably, an impact on grain and water supply, as huge portions of our arable land would have to be used for corn growing.
    • Still, using it as a supplement to existing fuels has proven to have a net positive impact on environmental concerns and energy use.
  • Ethanol Myths and Facts published by US Dept of Energy

Corn Yields per acre

  • 2010 → 165 bushels per acre
  • 2002 → 120 bushels per acres  [ 2010 yields are 37% higher than in 2002 ]
  • 1960 → 40 bushels per acre [ 2010 yields are 312% higher than in 1960 ]

Cellulosic Ethanol

  • Cellulosic ethanol is a biofuel produced from Lignocellulosic biomass
    • agricultural residues (unused portions of food plants)
    • wood residues (from lumber byproducts and forest clearing)
    • municipal paper waste (garbage!)
    • dedicated energy crops, which grow in substandard soil not suitable for standard agriculture.
  • Cellulolysis processes consist of hydrolysis on pretreated lignocellulosic materials, using enzymes to break complex cellulose into simple sugars such as glucose and followed by fermentation and distillation.
    • At this time, it’s an inefficient product due to the effort it takes to separate the sugar from the lignin (which has evolved to resist degradation, including chemical processes).
    • Many wood-based alcohols are also more difficult/time-consuming to ferment, than basic glucose (which makes standard ethanol)
  • This is a primary point of current research into alternative biofuels, as finding an efficient fermentation method would result in an abundance of ethanol fuel, with relatively little impact on our existing agriculture in the U.S.


  • Made from vegetable oils, animal fats or recycled greases.
  • Can be used as a fuel for vehicles in its pure form, but it is usually used as a diesel additive to reduce levels of particulates, carbon monoxide, and hydrocarbons from diesel-powered vehicles.
  • Blends of less than 20% biodiesel can be used in diesel equipment with no, or only minor modifications
  • Is produced from oils or fats using transesterification and is the most common biofuel in Europe.

Biodiesel chemistry

  • Triglycerides : Fats & Oils are esters [acids bonded to alcohols]
  • Triglycerides react with an alcohol → 3 Ethyl Esters of fatty acids and 4 glycerol
  • Decomposed in the presence of water [heat accelerates]
  • → Form mono-glycerides, di-glycerides and free fatty acids


  • fuels can be made from a wide variety of domestic energy resources including natural gas, coal, agricultural waste, energy crops, and trash.


  • Made from a variety of feedstock resources – including coal and natural gas as well as renewable resources like forest thinnings, agricultural waste and urban trash.
  • Beginning in 1965, pure methanol was used widespread in USAC Indy car competition, which at the time included the Indianapolis 500
  • The EPA contends that methanol is a safer transportation fuel than gasoline. It has projected that, because methanol is inherently more difficult to ignite than gasoline, fewer fires and casualties would result from traffic accidents.
  • Methanol lacks the carcinogens contained in gasoline. Its use would therefore contribute to public health. [windshield wiper fluid is over 33% methanol]

Natural Gas

  • alternative fuel vehicle that uses compressed natural gas (CNG) or, less commonly, liquefied natural gas (LNG)
  • The primary component of natural gas is methane (CH4), the shortest and lightest hydrocarbon molecule. It may also contain heavier gaseous hydrocarbons such as ethane (C2H6), propane (C3H8) and butane (C4H10), as well as other gases, in varying amounts. Hydrogen sulfide (H2S) is a common contaminant, which must be removed prior to most uses.
    • Highest combustion efficiency of any fossil fuel.
      • But still is not a renewable resource.
  • Worldwide, there were 11.4 million natural gas vehicles by 2009
    • Most common in: Pakistan, Argentina, Iran, Brazil, and India.
    • Only around 110,000 in USA (mostly public transportation), and only ONE commercially available model – the Honda Civic GX

General Flex Fuel Facts

  • Takes ~ $100 in parts to make a Gasoline car flex fuel compliant
  • In general, ethanol is less toxic and has higher energy density then methanol.
  • Methanol is less expensive to produce sustainably, and is a less expensive way to reduce the carbon footprint than ethanol.
  • When optimizing engine performance, fuel availability, toxicity and political advantage, a blend of ethanol, methanol and petroleum is likely to be preferable to using any of these individual substances alone.
  • The CEOs of the Big Three auto companies have repeatedly stated their willingness to commit to making 50% of new cars flex fuel vehicles or warranted to operate on biodiesel by 2012.
  • Methanol and ethanol both burn at lower temperatures than normal gasoline and are less volatile which at certain temperatures can make your automobile engine more difficult to start.

Additional Information

  • Citizens for Energy Freedom
  • Ethanol Across America
  • Open Fuel Standard Act : would require that 50 percent of new automobiles manufactured in 2014 be able to run on non-petroleum fuels in addition to regular gasoline. By 2017, the measure would require 97 percent of new vehicles to run on alternative fuels

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